This invention relates to valves for controlling the flow of fluids, and especially to a solenoid valve utilizing a self adjusting fluid control means to ensure accurate and precise fluid flow and where the fluid flow control means may easily be replaced without having to disassemble the entire valve.
There is a widespread demand for relatively small valves that can operate reliably, quickly, efficiently, and are capable of lasting for many millions of cycles. While there are applications for such valves in many fields, there are special requirements in chemical and biotechnology laboratories, ink jet printers, flux dispensing in manufacturing computer chips, and any other industries where accurate and precise fluid flow is necessary. In these applications, valves are opened frequently to allow the passage of various fluids therethrough in an exact and controlled fashion.
Bidirectional valves are known in the art where control of fluid flow is obtained independent of the direction of the flow of the fluid media. Such valves generally function by providing a flexible diaphragm which is directly attached to a plunger or other means such that the diaphragm is biased toward a valve seat closing the flow passage and thereby impeding fluid flow. The diaphragm is attached to the plunger in a rigid manner by using a threaded element or it is imbedded into the plunger. Such rigid attachment subjects the diaphragm to repeated opposing forces both at the point of attachment and at any radial compression point and may cause weakness in the diaphragm and failure thereof. In addition, some instruments use a plurality of the valves and it may be expensive and disruptive to find and replace individual valves whose diaphragm has failed.
Alternatively, U.S. Pat. No. 4,944,487 to Holterman discloses a diaphragm valve wherein the plunger is not attached to the diaphragm. The plunger biases the diaphragm against the valve seat and the diaphragm is maintained in place by radial compression along the perimeter of the diaphragm. Accordingly, Holterman""s valve operates passively in response to pressure from the flow medium when the plunger is retracted. The passive operation of the diaphragm may fail if the pressure of the fluid is insufficient to deform the diaphragm in order to allow the flow thereof. In addition, the chemicals contained within certain fluids may crystallize and attach the diaphragm to the valve seat. Furthermore, the radial compression exerted on the diaphragm may cause the failure thereof by puncturing same by the exertion of such pressure.
The prior art does not address the need for accurate control of the volume of fluid dispensed over many millions of cycles of use where the diaphragm is adapted to adjust upon each opening and closure thereby reducing the stress placed thereon. Therefore, there remains a long standing and continuing need for an advance in the art of valve assemblies that is simpler in both design and use, is more economical, sturdy, and efficient in its construction and use, and can quickly be installed and removed from instrumentation having a plurality thereof.
Accordingly, it is general object of the present invention to overcome the disadvantages of the prior art.
In particular, it is an object of the present invention to provide a valve apparatus that can operate with longevity.
It is another object of the present invention to provide a valve assembly that is economical to produce.
It is yet another object of the present invention to provide a valve assembly that is easily maintained but is sufficiently economical to replace.
It is another object of the present invention to provide a valve assembly that has a crisper opening and closing.
It is another object of the present invention to provide a valve assembly that provides easy adjustment of the rate of fluid flow therethrough.
It is another object of the present invention to provide a valve assembly that allows operation of the diaphragm in vacuum.
It is still another object of the present invention to provide a valve assembly that provides quick and exquisitely small valve movements with remarkable repetition relative to the volume of fluids passing therethrough.
It is another object of the present invention to provide a valve assembly that allows the adjustment of the diaphragm upon each opening and closing in order to achieve better fluid flow control.
It is yet another object of the present invention to provide a valve assembly that reduces the risk of leakage.
In keeping with the principles of the present invention, a unique self-adjusting diaphragm solenoid valve assembly is presented which overcomes the shortfall of the prior art. It is to be understood that the adjustable nature of the diaphragm may be incorporated into any valve assembly that is known in the art and is not limited to the solenoid valve assembly described herein.
The valve assembly has a cap that has an inner surface and an outer surface and a first and second aperture that extend from the inner surface and through the outer surface. On the outer surface, protrusions may be provided to connect the apertures to conduits for directing the flow of fluid to the apertures. On the inner surface, the apertures are symmetrically positioned and define a wall therebetween. A diaphragm that is preferably elastomeric is of sufficient size to simultaneously occlude the first and second apertures.
The cap is removably attached to a seat portion such that the diaphragm is maintained therebetween. The seat portion has a depression which is adapted to accommodate the diaphragm therein. The seat portion is further connected to the actuation region which is preferably a solenoid actuation means. A void extends axially through both said actuation region and the seat portion. A plunger means is received within said void and is adapted to connect with the diaphragm.
The diaphragm preferably has an elliptical shape and thus has a major and minor axis. Along the minor axis on a first side of the diaphragm there extends a first projection which is adapted to be received on the wall of the cap between the two apertures to seal between the same. On a second side of the diaphragm along is located the connecting means that connects the diaphragm to the plunger means in a pivoting manner.
The plunger means has an extension that connects a protuberance to the plunger means and the extension is smaller in diameter than the protuberance. The connecting means has a first prominence and a second prominence which extend parallel with the minor axis of the diaphragm and oppose one another to create an opening therebetween. A first lip and a second lip extend inwardly from first and second prominences and thereby narrow the size of the opening.
The opening is shaped to accommodate the protuberance therein in a tight fitting form and is further defined by the first and second lip. The first and second lip engage the protuberance and allow retraction of the diaphragm when the plunger is retracted. However, first and second lip allow enough opening therebetween to accommodate the extension and yet allow pivoting of the protuberance therein.
Thereby, when the plunger is retracted, the diaphragm is disengaged from the inner surface and wall of the cap and fluid is allowed to flow between the first and second aperture. When the plunger is reinserted, the diaphragm is biased against the inner surface and the wall and the pivoting attachment of the connecting means to the protuberance allow the diaphragm to adjust to achieve optimal occlusion of the first and second aperture to prevent fluid flow therebetween.